Switched-mode power supply converters suffer from electromagnetic interferences (EMI) caused by the loading and unloading of the converter's inductor. The electronic industry applies a number of regulations which specify a maximum level of acceptable EMI. In these regulations a high-frequency inductive current must be kept below a certain value.
Prior art practice is based on a passive low-pass input filter provided at the input stage of the power converter. Such a passive filter is typically made of two serial inductors and a capacitor, and is therefore relatively cumbersome.